205 
could not be arranged, side by side, in bundles within a com- 
mon sheath (or neurilemma), but must fuse together. 
Third objection.—The fibres in question are said to be dis- 
integrated fat; but to this, similar replies may be made; (a) 
the fibres are seen running in the nerve stems, enclosed in a 
common neurilemma, and giving off twigs to the glandular 
epithelial cells one after another ; (0) single fibres are observed 
with a detached sheath, which could not be the case with 
disintegrated fatty masses; (c) these fibres are, by means of 
their axis cylinder, directly continuous with the substance of 
the epithelial cells. 3 
If, then, there are fine fibres, stained with black by osmic 
acid, which are enclosed in bundles in one common sheath, 
then ramify and become continuous with the substance of 
epithelial cells, the only doubt which can remain is as to the 
reality of this asserted continuity; a point which Pfliger 
admits to demand the most minute scrutiny of the prepara- 
tions in question. 
The methods of investigation were as follows :— 
Salivary glands.—It must be remembered that osmic acid 
makes its way into the deeper parts of a tissue with difficulty, 
and that it renders the nerve-fibres especially brittle, so that 
these should be isolated before, not after the application of 
the osmic acid. A fresh submaxillary gland from the ox 
must be taken, and very fine sections made from it with a 
razor. These must be teased out in a solution of osmic acid 
of sp. gr. 1:003, and covered with a thin glass supported on 
a small drop of wax to avoid pressure on the specimen. A 
great many such preparations should be made and preserved 
in a moist chamber. The water as it evaporates may be re- 
placed by glycerine. They may be examined after twenty- 
four hours, when the fibres will be dyed black while the cells 
are pale. For the liver that of a dog or pig is best, and 
should be quite fresh. A large number of very fine sections 
should be made and placed, ten or twelve together, in watch 
glasses, filled with Beale’s carmine solution, and carefully 
protected from dust, evaporation, or mechanical injury. 
After fourteen days the sections are ready for examination, 
and remain so for some weeks. They are removed on the 
point of a preparing needle, and washed on a slide in a drop 
of osmic acid solution to remove the carmine; then placed 
in a fresh drop of osmic acid on a clean slide, when they 
may be very carefully teased out with needles. The sections 
are then to be examined with a low power of 150 to 200 
diameters, till a point is seen where the nerve-fibres appear to 
be continuous with epithelium, and this spot more closely 
